Although they didn't reach a goal of two million riders, thousands of bikers rolled through the Washington, D.C. area to mark the 12th anniversary of 9/11 on Wednesday.

The bikers -- riding with the group "Two Million Bikers to D.C." -- snarled traffic on the Beltway with a ride honoring the victims of the Sept. 11, 2001 terrorist attacks and the members of the military called to serve after the attacks.

'Two Million Bikers' to D.C.: Chopper Video

"Two Million Bikers to D.C." are riding through the city Wednesday, to honor the victims of 9/11 and the members of the military called to serve after the attacks. (Published Wednesday, Sept. 11, 2013)

Many participating riders were veterans who said they rode to protect Americans' freedom in the midst of tumultuous times.

"The enemy has a say when the war is over," said rider Pete Raymond. "I believe they're saying it's not, so we're here."

9/11 Flag Unfurled at Pentagon

The flag draped across the Pentagon following the 9/11 attacks was once again unfurled for the 12th anniversary of the attacks. (Published Wednesday, Sept. 11, 2013)

On their Facebook page, in all caps, the group said they will stand by the Constitution and Bill of Rights, adding that they're "against any fundamental transformation of America."

America Remembers 9/11

The ride began at Harley Davidson of Washington in Fort Washington, Md., at 11 a.m. Many drivers pulled over along the side of the highway to wave and take pictures.

Santana Sensenna was one of them.

"I could stay here for half an hour; I don't care; this is America," he said while stuck in the traffic.

The bikes rolled in a steady stream for 50 straight minutes before heading to the Beltway. But the ride wasn't smooth for everyone. At one point, a motorcycle went down on the Outer Loop in the Bethesda area, causing traffic to back up for miles.

At the National Mall, another motorcyclist ran his bike into the back of a pedicab.

"I think the heat got to me and I kind of blacked out a little bit," said the rider, Bill Eisenheart. "You know, I didn't see him."

Another group of participants made their way up Interstate 95 in Stafford around 9 a.m. and reached D.C. about two hours later. The northbound lanes of I-95 at exit 143 in Stafford County were closed for about 15 minutes as motorcyclists began their trip.

But the traffic concerns didn't overwhelm the riders. The overarching theme of the day was remembering what happened 12 years earlier.

Mortello, a Desert Storm veteran and full-time firefighter, came down from New Jersey to be a part of the ride. He remembers vividly what the day was like for one of his friends in New York City who rushed into the World Trade Center to help.

"He had a woman with third-degree burns. As he came through a tunnel, one tower collapsed. The tunnel that he was in collapsed -- missed him by about two feet. Buried everybody else that was with him," Mortello said.

He says some friends have still not gotten over that day, and that's why he was riding Wednesday.